FS-120S Valve Spring Retainer OS45560310 by O.S. Engine  [OS45560310]

Retainer for FS-series valve springs

This valve spring retainer is a direct replacement item listed under O.S. Engine engine parts and identified by model OS45560310 and FS-120S naming. It secures valve springs on compatible FS-series glow engines and is intended for use during engine service, repair, or routine rebuilds.

In practical terms, the retainer keeps valve springs seated and aligned during engine operation, so checking it as part of regular maintenance reduces the chance of valve timing problems. When fitting a replacement, confirm the part number OS45560310 matches your engine parts list and examine nearby valvetrain components for wear.

For tuning and setup, the retainer does not change valve timing but provides reliable spring retention when you adjust valve clearances or swap springs. Use basic workshop precautions when handling small valvetrain parts and follow the engine maker's service intervals.